Method of making shafts



Sept. 29, 1936. J4 E. MCLAUGHLIN METHOD oF MAKING SHAFTS Filed April-1s, 1933 2 sheets-she.;v

Sept.v 29, 1936- J. E. MCLAUGHLIN Y 2,055,771

METHOD OF MAKING SHAFTS Fild April 18, 1953 2 sheets-sheet 2 INVENTOR Patented Sept. 29, 1936 UNITED STATES METHOD F MAKING SHAFTS Joseph E. McLaughlin,

Aluminum Company of America,

Arnold, Pa., assignor to Pittsburgh,

Pa., a corporation of yPennsylvania Application April 18,

Claims.

The invention relates to a method of fabricat-v ing shafts of novel cross sectional configuration from previously formed seamless tubing. More particularly, it concerns the production .of a shaft 5' of seamless convoluted tubing characterized by shaft. Probably the most serious difficulty which has been encountered in the attempt to produce a metal shafted club which would have somee thing of the same feel as a wood shafted club is that of obtaining -the desired torsional characteristics. It is a well known fact that the usual metal shafted club which is produced from a tapered or stepped tubing, usually of simple circular cross section, doesnot have the feel of a wood shaft and does not whip" at the moment of impact with the ball in the manner of a wood shafted club. This disadvantage of the metal shaft has generally been ascribed to the fact that the torsional rigidity of the metal shaft is toc high. Yet, it has not been considered feasible to decrease the ytorsional rigidity tothe desired point without too great a sacrifice of bending strength.` As a consequence, those golfers who Wish to use metal shafted clubs have been compelled to adjust themselves to the different feel of the club, and it isclaimed by many that the lack of proper torsional characteristics diminishes the distance of the drive which can be made with a given type of club.

It is, therefore, an object of this invention to provide a form of metal shaft which possesses the desired torsional characteristics, having an increased bending moment as compared with ordinary tubing of like size and material, yet having less torsional rigidity than that possessed by ordinary tubing.

y More broadly, it is an object of my invention to provide a method of fabricating a seamless tube of novel cross sectional figuration which is characterized by a smooth cylindrical outer surface and portions folded inwardly toward the center,

with the inwardly folded portions preferably meeting adjacent the center of the tube. The invention has been developed with reference to 1933, Serial No. 666,697

(Cl. S29-156) the formation of shafts of aluminum, and it has been found that this metal 4is particularly well adapted to fabrication .in accordance with the method herein described. Other objects and advantages will appear from the following description .when taken in connection with the accompanying drawings.

In the drawings Fig. l is a diagrammatic view in central vertical cross Section illustrating the method of drawing a previously formed polygonal tube through a series of circular die openings provided with flaring entrance portions. Fig. 2 is an end view of the polygonal tube. Fig. 3 is an end view of the finished shaft. Fig. 4 is an enlarged cross section of the partially formed tube taken on the line lV-IV of Fig. 1; and Fig. 5 shows a similar cross section at a more advanced stage of the forming operation taken on the line V-V of Fig. l. Fig. 6 represents an elevational view of a completed shaft of stepped formation.

Fig. 7 is an isometric view partially in central vertical cross section illustrating an alternative vmethod whichcomprises drawing a previously formed polygonal tube through a single die block provided with a circular die opening having a long flaring entrance portion. y

Fig. 8 illustrates a modified form of apparatus which may be used to carry out the method indicated in connection with Figs. 1 and 7.

Figs. 9 .to 12, inclusive, are elevational views with cross sectional views appurtenant, illustrating a further modification of my invention. Fig. 9 is an elevational View of a round tube. Fig. 10

is a similar view with cross sectional views appurtenantshowing the form of the shaft at the conclusion of the first step of the modified method. Fig.' 11 is a similar view with cross sectional views appurtenant showing the form of the shaft at the conclusion of the second step of the modified method; and Fig. 12 is a similar view with cross sectional views appurtenant of the finished shaft as produced in accordance with this modified method. Fig. 13 is a fragmentary view in central vertical cross section showing to a somewhat enlarged scale the formation of the shaft of Fig. 12 at the point where the convoluted portion thereof blends into a portion of regular circular cross There is shown in Fig. l a series of die blocks I, 2, and 3, which are provided with circular openings 4, 5, and 6 respectively'. The diameter that of the shaft which is to be produced. The entrance portion of each die opening is flared of the circular opening 6 of dief3 'corresponds to f outwardly as indicated at 'I in die block I. The particular shape of the flaring portion 'I is subject to some variation, but I prefer that it be substantially cone shaped, with the surface of the cone at an angle of approximately 10 to the axis thereof. At its widest portion it should be slightly greater in diameter than the diameter or longest transverse dimension of the tube which isto be introduced.

As indicated in Fig. 1, the shape of the aring opening 1 at the entering face of the die I is substantially circular. However, this may be varied to conform more or less with the shape of the previously formed tube which is to be drawn. Furthermore, if the flared entrance to the die I is made of suitable polygonal shape, preforming of the tube to a polygonal shape may be eliminated and a plain circular tube can be fed into the die block I. Again, it is not strictly necessary that the exit portions 4 and 5 of the die blocks I and 2, respectively, be circular. It is an essential feature, irrespective of the shape of the openings of the die blocks I and 2 or of the shape of the entrance portion 8 of the die block 3, that the exit portion 6 of the die block 3 -be substantially circular or curvilinear in cross section. I have found that if a polygonally shaped tube, such as a tube which is hexagonal or octagonal in cross section, is drawn through a die opening or series of die openings which, at the narrowest point, is substantially circular, it is possible to produce a shaft of unique cross section. The shaft so produced (Fig. 3) is characterized by inwardly folded portions 9 and a smooth cylindrical outer surface I Il. The form of the shaft will be more fully described below in connection with Fig. 7. The shaft is further characterized by the sharp line contact II at the outer surface III of the tube, the relationship between the outside perimeter of the previously formed polygonaly tube I2 to the circumference of the exit portion 6 of the die 3 being such that the meeting edges of the folds 9 are forced so tightly together'as to form sharp corners which blend smoothly into the outer cylindrical surface III of the shaft.

It is also possible, through selecting the proper size of die opening 6 for a given size of polygonal tube I2, to force the inwardly folded portions 9 'together until they meet adjacent the center of the shaft, as shown in Fig. 3. The folds so produced serve to increase the transverse bending strength of the shaft, and yet, by reason of the fact that the openings between each fold face outwardly, they make possible a certain amount of give in torsion. 'I'he give is retarded to a certain extent by the frictional engagement between the walls of the fold, and by regulating the area of contact between the folds it is possible to vary the torsional resistance within certain limits.

It will, of course, be understood that instead of the octagonal tube I2 shown in Fig. 2, it is possible to use a previously formed tube having a greater or less number of sides. If a hexagonal tube is used, there will be produced three double folds instead of the four indicated in Fig. 3. In the case of a square tube there would be produced two double folds. It is also not strictly necessary that the sides of the polygon be fiat, because if the previously formed tube were of a cross section such as indicated in Figs.V 4 or 5, for instance, it would still be possible to produce a shaft of the desired configuration. It should, therefore, be understood that the term polygonal as used herein is intended to include such substantially polygonal structures as indicated in Figs. 4 or 5. The gist of the method consists in subjecting the tube to collapsing pressure, which pressure is applied at predetermined points-this predetermination being governed by the shape of the polygonal tube itselfwhereby the walls of the tube are caused to collapse inwardly, and continuing to reduce the circumference of the partially collapsed tube by progressively contracting the circle of application of pressure with respect to the axis of the tube until the edges of the inwardly collapsed portions meet to form a smooth cylindrical outer surfaceon the finished tubing. This result may be accomplished through the medium of a series of die blocks such as has been described with reference to Fig. 1; or it may be accomplished by means of a single die block such as illustrated at I3 in Fig. 7.

In connection with Fig. 7, it will be noted that Fig. 4 o f the drawings, which has previously been described as a section taken on the line IV--IV of Fig. 1, also shows the cross section of the partially formed tube taken on a line represented at IV-IV of Fig. 7; and Fig. 5 shows a similar cross section at a more advanced stage of the forming operation, as represented by the plane V-V of Fig. 7. The general concept of the invention and the exact form of the shaft produced are clearly illustrated in Fig. 7. 'Ihe die block I3 is provided with a substantially circular opening I4 and a flaring entrance portion I5. The circular opening I4 corresponds in diameter to the diameter of the shaft which is to be produced. The par- 'ticular shape of the flaring portion I5 is subject to some variation, but, as was said in connection with a description of the flaring opening I of the die block I of Fig. 1, I prefer that it be substantially cone shaped. At its widest portion it should be slightly greater in diameter than the diameter or longest transverse dimension of the tube I2' which is to be introduced.

Also parallel to the description of Fig. 1 and still with reference to the particular disclosure of Fig. 7, it isto be noted that the circular form of the entering face of the flaring opening I5 may be varied to conform more or less with the shape of the previously formed tube which is to be drawn; and if the flared entrance I5 be of suitable polygonal shape, preforming of the tube to a. polygonal shape may be eliminated so that a plain circular tube can be fed into the die block I3. Whatever the shape of the entrance portion I5, it is an essential feature that the exit portion I4 of the die be substantially circular or curvilinear (it may be elliptical) in cross section. The .method illustrated by Fig. 7 is essentially the same method as that illustrated by Fig. 1. The shaft produced is characterized by inwardly folded portions 9' and a smooth cylindrical outer surface I0. 'I'he outwardly facing opening I6 between each fold 9 is tightly closed at the outer surface I0' of the tube, the relationship between the outside perimeter of the previously formed polygonal tube I2 to the circumference of the exit portion I4 of the die being such that the meeting edges of the folds 9' are forced so tightly together as to form sharp corners I'I which blend smoothly into the outer cylindrical/surface I0' of the shaft. It is also possible, through selecting the proper size of die opening I4 for a given size of polygonal tube I2', to force the inwardly folded portions 9' together until they meet adjacent the center of the shaft as at I8.

It has now been seen that the shaft Just demodification is shown in Fig. 8, in which pattern rolls are shown in place of dies. In so far as 'die drawing andY die rolling produce equivalent results, they are to be considered as equivalents in the definition of the present invention. It is,

therefore, intended that wherever the term die is used, it will in its full signification include -not only a simple die but also a die which is made up of pattern rolls. l

'I'he meeting portions of a set of pattern rolls are shown at I9 jin Fig. 8. These pattern rolls are made to form a circular opening 20. The method here indicated is generally referred to asdie rolling, as contradistinguishedfrom die drawing.

The finished shaft may be'further reduced by drawing through a series of dies in order to form inwardly folded portion 9 or 9' will meet in tight pressed engagement at the smaller end of the shaft but be slightly separated at the larger end, while throughout the entire length ofthe shaft the desired smooth cylindrical outer surface is maintained. 'I'he nished shaft, as described in connection with Fig. "I, may be further processed by drawing it through another die to give it a' square shape or the shape of a square with roundl ed corners. In this event, the line of contact II' between the meeting edges of the folds 9' at the surface of the' shaft will preferably be disposed at the corners ofthe square. That is to. say, I contemplate further processing of the shaft b y passing it through a polygonal die which would serve to flatten the outer walls of the shaft between the folds, while maintaining the sharp line contact between the meeting edges I1 of the folds where they blend into the outer surface of the shaft.

Rference is now had to the modification illustrated in Figs. 9 to 13, inclusive. This modification shows the possibility of localizing and controlling the torsional characteristics in a shaft fabricated in accordance with my process. If, for instance, it should be found desirableto decrease the torsional resistance of a golf club shaft near the head of the club, while leaving the remainder of the shaft more rigid in torsion, or to effect the decreasevin torsional resistance near the' grip or elsewhere, this can readily be accomplished by means of the method here indiy cated. A round tube of suitable diameter (Fig. 9) is drawn into steps 2l, 22, and 22 of varying diameter proportioned and arranged in accordance with the length of that section of the shaft which is to be provided with reentrant folded portions infaccordance with the method already described. The portion 22 of the tube is left at a diameter larger than that of the other portions and is drawn through a die to give it an octagonal or other suitable polygonal shape ln accordance with any of the. methods which are now known to the art for accomplishing this purpose. This step of the process produces a shaft of the form y shown in Fig. l0, having a portion of its length polygonal in cross section as at 22, and having other portions of its length substantially circular in cross section as at 2l and 23.

The shaft of Fig. 10 is then drawn through a circular die or a series of circular dies such as shown in Fig. '7 and Fig. 1, the exit portion of th die or of the final die being of such size that reentrant portions are formed and folded to- .gether in the portion 22' of the shaft as indicated in Fig. 1l. The shaft is then tapered or step drawn over its entire lengthand trimmed to give it the desired final form. Fig. l2 shows a tapered shaft. Fig. 13 shows the cross sectional configuration of the shaft at the point where (in Fig. 12) the convoluted portion 22" of the shaft joins the simple circular section 23". It will be seen that the outer surface of the shaft is perfectly smooth and unbroken at the juncture between the two sections. Upon close inspection of the shaft produced in accordance with this particular method,` a line line is discernible at the meeting edges of the folds, as at 24 in Fig. 12. This line 24 blends into and disappears at the beginning of the circular portions 2|" and 23" of the shaft. The completed shaft as shown in Fig. 12 is thus provided with a portion 2 I which is quite rigid in torsion, a portion 22" of decreased torsional resistance, and a portion 23" which, lik the portion 2|", is relatively stiff in torsion. It is a feature of my invention, on the other hand, that the bending strength of the portion 22" is high. 'I'his means that by my method it is possible to produce a shaft which, while strong, is yet suillciently resilient to give the characteristics desired in a shaft for golf clubs and lthe like.

I claim: 1. The method of producing convoluted tubing having a smooth cylindrical outer surface which comprises subjecting a previously formed polygy onally shaped tube to\ radial pressure effective initially only at corners of the polygon, the points of application of pressure lying in a plane perpendicular to the axis of said tube and approximately defining the circumference of a circle. whereby the walls of said tube are caused to collapse inwardly at predetermined points, and continuing to reducev the circumference of the partially collapsed tube by progressively contracting the circle of application oi pressure with respect to the axis of said tube until the edges of the inwardly collapsed portions meet' to form a smooth cylindrical outer surface on the finished tubing.

2. The method of producing convoluted tubing having a smooth Vcylindrical outer surface which comprises passing a polygonally shaped tube through a substantially circular opening the circum'ference of which is appreciably less than the perimeter of said polygonally shaped tube whereby the walls of said tube are caused to collapse inwardly at predetermined points, and continuing to reduce the circumference of the'partially collapsed tube by passing it through openings of progressively smaller circumference until the edges of the inwardly collapsed portions meet to form a. smooth cylindrical outer surface on the finished tubing. v

3. The method of producing shafts for golf clubs and the like which comprises forming a tube which for a portion of its length is substantially circular in cross section and which for :mother portion of its length is 'polygonal in cross section, subjecting the polygonally shaped portion to radial pressure effective initially only at corners of the polygon, the points of application of pressure lying in a plane perpendicular to the axis of said tube and approximately defining the circumference of a circle, whereby the walls of said tube are caused to collapse inwardly at predeterminedlpoints, and continuing to reduce the circumference of the partially collapsed tube by progressively contracting the circle of application of pressure with respect to the axis of said tube untilthe edges of the inwardly collapsed portions meet to form a smooth cylindrical outer surface blending into the outer surface of said other portion of the tube which is substantially circular in cross section.

4. 'I'he method of producing shafts for golf clubs and the like which comprises forming a tube which for a portion of its length is substantially circular in cross section and which for another portion of its length is polygonal in cross section, passing the polygonally shaped portion of the tube through a substantially circular opening, the circumference of which is appretube.

5. The method of producing convoluted tubing having a smooth outer surface which comprises subjecting a polygonally shaped tube to pressure e'ective initially only on the corners of the polygon, and progressively decreasing the diameters of said tube to collapse the sides of said polygon inwardly until the edges of the collapsed portion meet to form a smooth outer surface on the tube.

JOSEPH E.'MCLAUGH1.IN. 

